For the site coordinator managing the daily reality of a clinical trial, the Investigator Site File is the document collection that never quite goes away. Forms to file. Certificates to renew. Logs to update. And somewhere in the background, the knowledge that an inspector or monitor could ask to see it at any time.
Most site teams know the ISF exists. Fewer have a clear picture of everything it must contain, how it connects to the sponsor’s Trial Master File, and what “well-maintained” actually means when someone qualified to judge it is sitting across the table.
This guide covers all of it.
What is an Investigator Site File?
An Investigator Site File (ISF) is the documentary record maintained at an investigational site during a clinical trial. It contains the essential documents that demonstrate the site’s conduct of the trial in accordance with Good Clinical Practice (GCP) and the approved protocol.
The ISF is sometimes referred to as the site file, the site master file, or the investigator file. Regardless of the name, the regulatory requirement is the same: under ICH E6(R2) GCP guidelines, every investigational site must maintain a complete, current, and accessible set of essential documents for the duration of the trial and for the required retention period after close-out.
The ISF is not a static archive. It is a living document collection that changes as the study progresses — new protocol versions, updated delegation logs, renewed GCP certificates, monitoring visit reports, and corrective action documentation all generate new or updated records that must be filed accurately and promptly.
How does the ISF relate to the Trial Master File?
The ISF and the Trial Master File (TMF) are two sides of the same record. The TMF is maintained by the sponsor and contains the complete study-level documentation. The ISF is maintained at the site and contains the site-level documentation.
For many documents — protocol versions, informed consent forms, IRB/IEC approvals, investigational product certificates — both the sponsor and the site hold a copy. In a compliant study, these copies match. The same version, filed in both places, contemporaneously.
When they do not match — when the site’s consent form is a different version from the one in the TMF, or when the monitoring visit report in the ISF is dated differently from the copy in the TMF — that is a cross-reference discrepancy. It is one of the most consistently cited categories of inspection finding across EMA GCP inspections.
This is why the Menken Trials eISF is directly connected to the eTMF and monitored by Menka AI simultaneously — so discrepancies between the two are caught the moment they appear, not discovered during monitoring or at inspection.
What must an ISF contain?
The contents of an ISF are defined by ICH E6(R2) and the applicable regulatory requirements for the country or countries in which the site is operating. The following documents are universally expected across major regulatory jurisdictions:
Protocol and amendments. The current approved version of the protocol and all amendments, with evidence of IRB/IEC approval for each version.
Investigator Brochure. The current version, with evidence of receipt at the site.
Informed consent forms. All versions used at the site, with documentation of IRB/IEC approval for each version and evidence of the date from which each version was used.
IRB/IEC approvals and correspondence. Initial approval, re-approvals, and any correspondence with the ethics committee relevant to the conduct of the trial.
Regulatory authority approvals. Applicable national or regional approvals for the conduct of the trial at the site.
Delegation log. A current log of every task delegated by the principal investigator to each member of the site team, with start and end dates for each delegation. The delegation log must be cross-referenced with training records — a person may only be delegated a task they have been trained for.
Training records and GCP certificates. Evidence of GCP training for every member of the site team conducting trial-related activities. GCP certificates must be current for the period during which the person was active on the study.
Investigator CVs. Current CVs for the principal investigator and all co-investigators. Most sponsors require a CV update at least annually.
Financial disclosure documentation. Completed financial disclosure forms for all investigators, as required by applicable regulations.
Investigational product accountability logs. Records of receipt, dispensing, return, and destruction of all investigational product at the site.
Monitoring visit reports. Reports for every monitoring visit, including close-out visits, with any required corrective action documentation.
Correspondence. Significant correspondence between the site and the sponsor, CRO, IRB/IEC, and regulatory authorities relevant to the conduct of the trial.
Screening and enrolment logs. Records of all subjects screened, enrolled, and withdrawn, with reason codes where applicable.
Subject identification log. A confidential log linking subject identification codes to subject identities, held securely at the site.
Protocol deviation log. A record of all protocol deviations at the site, with classification, assessment, and reporting documentation where required.
What do monitors and inspectors look for in an ISF?
Understanding what a Clinical Research Associate (CRA) or GCP inspector is checking when they review your ISF is the most direct path to maintaining one that holds up under scrutiny.
Contemporaneity. Documents should be filed at the time of the activity they document. A monitoring visit report filed six weeks after the visit, or a consent form scanned three months after it was signed, carries a metadata timestamp that tells a story. Late filing is a finding.
Delegation-to-training alignment. Every task on the delegation log must have a corresponding training record. If a sub-investigator is delegated to obtain informed consent but has no evidence of consent procedure training in the ISF, that is a finding — regardless of whether the consent itself was properly obtained.
Current qualifications. GCP certificates and CVs must be valid for the period during which the person was active on the study. An expired GCP certificate, even by a single day, that overlaps with a period of trial activity is a qualification gap.
Version accuracy. Consent forms, protocols, and investigational product labels must reflect the version that was approved and in use at the time the document was generated. A consent form using protocol version 3.0 language signed after version 3.1 was approved is a version control finding.
Completeness. Every required document for the site’s phase of the trial — initiation through close-out — should be present. Gaps in the file are mapped against the timeline of study activities. An empty monitoring visit slot when visit records show a monitoring visit took place is an immediate question.
The most common ISF deficiencies
Across EMA GCP inspections and CRA monitoring visits, these are the ISF issues that appear most consistently:
- Delegation log entries with no corresponding training record
- Expired GCP certificates covering active study periods
- Consent forms referencing superseded protocol versions
- Monitoring visit reports filed significantly outside the agreed timeframe
- Missing or incomplete investigational product accountability entries
- Protocol deviations not documented or reported as required
- Investigator CVs not updated within the required annual cycle
- IRB/IEC re-approval documentation missing for studies running beyond the initial approval period
Every one of these is detectable before inspection — if someone is actively checking. The challenge for most site teams is that the workload of running a study leaves little capacity for the continuous administrative oversight that would catch these issues as they arise.
How Menka AI monitors your ISF
The Menken Trials eISF is monitored by Menka AI in real time — the same way the eTMF is monitored. Every document filed at the site is checked immediately for completeness, version accuracy, and cross-references against the delegation log and training records.
When a GCP certificate is approaching expiry, Menka AI sends a reminder at 60 days and again at 30 days. When a delegation log entry has no corresponding training record, Menka AI flags it the moment the delegation is entered. When a consent form version does not match the approved version in the eTMF, Menka AI catches the discrepancy — before a monitor or inspector does.
The eISF and eTMF are directly connected, so Menka AI monitors both sides simultaneously. Discrepancies between the site file and the sponsor file are caught automatically, not discovered during close-out.
Site teams using Menken Trials describe the result the same way: less time spent on document administration, more certainty about where the study actually stands.
Frequently asked questions
Who is responsible for maintaining the ISF? The principal investigator is responsible for the ISF at the site. In practice, day-to-day maintenance is typically delegated to a site coordinator or trial coordinator, with the principal investigator retaining responsibility for oversight and accuracy. The sponsor or CRO is responsible for ensuring, through monitoring, that the ISF is being maintained correctly.
Can an ISF be electronic? Yes. An eISF (electronic Investigator Site File) is accepted by major regulators, including the EMA and FDA, provided the system meets the requirements for electronic records and electronic signatures under applicable regulations. The system must have a validated audit trail, access controls, and data integrity protections. The Menken Trials eISF meets these requirements.
How long must an ISF be retained after the trial? ISF retention requirements mirror those of the TMF. Under ICH E6(R2), essential documents must be retained for at least two years after the last approval of a marketing application, or for at least two years after formal discontinuation of clinical development. Sites should confirm the specific retention requirements with the sponsor, as these can exceed the minimum regulatory requirement. The retention agreement should be documented in the clinical trial agreement.
What is the difference between the ISF and the TMF? The TMF is the sponsor-level file; the ISF is the site-level file. For documents that exist in both — protocol versions, consent forms, monitoring visit reports — the two should be mirror images of each other. The sponsor is responsible for the TMF; the site is responsible for the ISF; the sponsor has oversight responsibility for the ISF through monitoring. Discrepancies between the two are a common inspection finding.
What happens if the ISF is found to be deficient at inspection? Deficiencies found during a GCP inspection are classified by severity. Minor deficiencies may require a corrective action plan. Major or critical deficiencies can trigger follow-up inspections, require study data to be excluded from a regulatory submission, or in serious cases result in regulatory sanctions. Prevention — through continuous maintenance — is significantly less disruptive than remediation after a finding.
How often should the ISF be reviewed? The ISF should be reviewed continuously, not periodically. Waiting for a monitoring visit or a pre-inspection sweep to identify deficiencies means operating with an unknown level of compliance risk throughout the study. An eISF with continuous automated checking — like the Menken Trials eISF — removes the dependency on scheduled reviews by catching issues the moment they occur.
See what Menka AI would find in your ISF
We run 15-minute sessions where Menka AI reviews a real study scenario relevant to what your team is running and shows you what she finds. No preparation needed on your side. No pitch.
Menken Trials is a clinical trial compliance platform built by people who have worked in clinical research. The Menken Trials eISF is directly connected to the eTMF and monitored by Menka AI in real time.
